Neumann Vintage U87 Clone : Build Thread.

[jandoste]

Hey Guys,
I finished the baby but it's so low sound that I am hearing... I calibrated it so I got 11.4V and 48V also well
the other voltages are like below;

Phantom:  47.86V
Top of R18: 47.8
Bot of R19: 47.8
Node R18/R19: 46.68V
Zener : 23.83V
node R12/R14: 19.71
FET Drain :  0.42V   
FET Source: 0.32V

I didn't put yet 10K resistor...
any idea what's happen here? 

Thanks

 

[poctop]

Hey Guys,
I finished the baby but it's so low sound that I am hearing... I calibrated it so I got 11.4V and 48V also well as like below;

Phantom:  47.86V
Top of R18: 47.8
Bot of R19: 47.8
Node R18/R19: 46.68V
Zener : 23.83V
node R12/R14: 19.71
FET Drain :  0.42V   
FET Source: 0.32V

I didn't put yet 10K resistor...
any idea what's happen here? 

Thanks

FET Drain :  0.42V    this looks strange it should be 11-13V like the calibration might be a typo or wrong reading,
What transformer are you using if using the T13 did you check the Errata on page 1
Let us know,
Best,
dAn

 

[jandoste]

Hey Dan,
You're right! it was a typo! I'm using a Cinemag CM-2480. I checked everything again again again but nothing wrong
I used 10k for R11 but the problem is there! baddddd
Thanks

Hey Guys,
I finished the baby but it's so low sound that I am hearing... I calibrated it so I got 11.4V and 48V also well as like below;

Phantom:  47.86V
Top of R18: 47.8
Bot of R19: 47.8
Node R18/R19: 46.68V
Zener : 23.83V
node R12/R14: 19.71
FET Drain :  0.42V   
FET Source: 0.32V

I didn't put yet 10K resistor...
any idea what's happen here? 

Thanks

FET Drain :  0.42V    this looks strange it should be 11-13V like the calibration might be a typo or wrong reading,
What transformer are you using if using the T13 did you check the Errata on page 1
Let us know,
Best,
dAn

 

[poctop]

Hey Dan,
You're right! it was a typo! I'm using a Cinemag CM-2480. I checked everything again again again but nothing wrong
I used 10k for R11 but the problem is there! baddddd
Thanks

Hey Guys,
I finished the baby but it's so low sound that I am hearing... I calibrated it so I got 11.4V and 48V also well as like below;

Phantom:  47.86V
Top of R18: 47.8
Bot of R19: 47.8
Node R18/R19: 46.68V
Zener : 23.83V
node R12/R14: 19.71
FET Drain :  0.42V   
FET Source: 0.32V

I didn't put yet 10K resistor...
any idea what's happen here? 

Thanks

FET Drain :  0.42V    this looks strange it should be 11-13V like the calibration might be a typo or wrong reading,
What transformer are you using if using the T13 did you check the Errata on page 1
Let us know,
Best,
dAn

if you are a 50-55db of gain on your pre to operating Level and the noise is good then you might not have a problem ,
remember the U87A is not a Hot mic and sounds very musical and warmth,
what is the chain and gain setting you use or need

how did you connect your cinemag on wich pad.

xlr side = wich color and capsule side wich colour ?

remember that the ratio is 10:1 and not 1:10

 

[jandoste]

Thanks Dan,
The level is really low I tried it with Neve 1073 and Avid HD Omni so it's same level also XLR pins 2 and 3 are shorting! I don't understand why?
I lost my mind with the XLR connexion: is that right:
Pin 1 to grnd 3 (PCB)
Pin 2 to Cold 2 ( PCB)
Pin 3 to Hot 1 (PCB) Right no?


I uploaded two pictures here;





Thanks

if you are a 50-55db of gain on your pre to operating Level and the noise is good then you might not have a problem ,
remember the U87A is not a Hot mic and sounds very musical and warmth,
what is the chain and gain setting you use or need

how did you connect your cinemag on wich pad.

xlr side = wich color and capsule side wich colour ?

remember that the ratio is 10:1 and not 1:10

 

[poctop]

Pin 1 to grnd 3 (PCB)
Pin 2 to Cold 2 ( PCB)
Pin 3 to Hot 1 (PCB) Right no?

No,
the corret answer is gnd , hot , cold are labelled on the pcb.
pin 1 is gnd
pin 2 is hot
pin 3 is cold

RT = red from cinemag 2480 Transfo
SW = brown from cinemag 2480 TRansfo
WS = yellow from cinemag 2480 Transfo
BL =  orange fromcinemag 2480 Transfo,

you should not have a short between pin 2 and pin 3 ,
remove the secondary of your transformer, verify that you dont have short a this moment the pcb itlsef.

Hope this helps,
Best,
Dan,

 

[poctop]

For those Having issues getting the 1G resistor at a nice price ,

here is a suggestion ,

Best,
DAn,

 

[jandoste]

Thanks Dan,
It was again a typo! it was right my xlr connection. I'll try to move the secondary of transformer.

Pin 1 to grnd 3 (PCB)
Pin 2 to Cold 2 ( PCB)
Pin 3 to Hot 1 (PCB) Right no?

No,
the corret answer is gnd , hot , cold are labelled on the pcb.
pin 1 is gnd
pin 2 is hot
pin 3 is cold

RT = red from cinemag 2480 Transfo
SW = brown from cinemag 2480 TRansfo
WS = yellow from cinemag 2480 Transfo
BL =  orange fromcinemag 2480 Transfo,

you should not have a short between pin 2 and pin 3 ,
remove the secondary of your transformer, verify that you dont have short a this moment the pcb itlsef.

Hope this helps,
Best,
Dan,

 

[jandoste]

Ok, I found the bug! It was the FET so i changed it everything is work now expect I got a big and nice hummm now 
Do you think that the cinemag do that?
Thanks

 

[poctop]

Ok, I found the bug! It was the FET so i changed it everything is work now expect I got a big and nice hummm now 
Do you think that the cinemag do that?
Thanks

could you exlplain what you think the problem was with the FET,

have you installed the mic shell when testing it cause it will sure hum crazy with no shell,

dan,

 

[jandoste]

Thanks Dan,
the wiper of FET was broken hahahaaaaaa!
Do you think that I must re-calibrate it?
Thanks

Ok, I found the bug! It was the FET so i changed it everything is work now expect I got a big and nice hummm now 
Do you think that the cinemag do that?
Thanks

could you exlplain what you think the problem was with the FET,

have you installed the mic shell when testing it cause it will sure hum crazy with no shell,

dan,

 

[poctop]

Thanks Dan,
the wiper of FET was broken hahahaaaaaa!
Do you think that I must re-calibrate it?
Thanks

Ok, I found the bug! It was the FET so i changed it everything is work now expect I got a big and nice hummm now 
Do you think that the cinemag do that?
Thanks

could you exlplain what you think the problem was with the FET,

have you installed the mic shell when testing it cause it will sure hum crazy with no shell,

dan,

The FET has no Wiper , the Potentiometer Does,
the way to do this is to wire the pot for calibration and then install the resistor ,
the new version of the board allow a much better package for the pot or the resistor , <
yes you will need to recalibrate to make sure you have secure connection for R11 (pot or resistor)

Let me know how you make out,
Best,
dAn

 

[jandoste]

Hey Dan,
I got a bad news that I don't understand how it could possible Pin 2 and Pin 3 are shorting and I can't find how I can't find a solution can't understand... the bad news is that my HD Omni's 1st and 2nd channel are dead! :-[ what was the reason I don't know... maybe the shorting issue did it but I'm not sure... Anyway I can't find the problem! everything looks like ok but there is something wrong with my build...
Thanks

PS: wiper=> the second pin of 2N3819

Thanks Dan,
the wiper of FET was broken hahahaaaaaa!
Do you think that I must re-calibrate it?
Thanks

Ok, I found the bug! It was the FET so i changed it everything is work now expect I got a big and nice hummm now 
Do you think that the cinemag do that?
Thanks

could you exlplain what you think the problem was with the FET,

have you installed the mic shell when testing it cause it will sure hum crazy with no shell,

dan,

The FET has no Wiper , the Potentiometer Does,
the way to do this is to wire the pot for calibration and then install the resistor ,
the new version of the board allow a much better package for the pot or the resistor , <
yes you will need to recalibrate to make sure you have secure connection for R11 (pot or resistor)

Let me know how you make out,
Best,
dAn

 

[poctop]

Hey Dan,
I got a bad news that I don't understand how it could possible Pin 2 and Pin 3 are shorting and I can't find how I can't find a solution can't understand... the bad news is that my HD Omni's 1st and 2nd channel are dead! :-[ what was the reason I don't know... maybe the shorting issue did it but I'm not sure... Anyway I can't find the problem! everything looks like ok but there is something wrong with my build...
Thanks

PS: wiper=> the second pin of 2N3819

Thanks Dan,
the wiper of FET was broken hahahaaaaaa!
Do you think that I must re-calibrate it?
Thanks

Ok, I found the bug! It was the FET so i changed it everything is work now expect I got a big and nice hummm now 
Do you think that the cinemag do that?
Thanks

could you exlplain what you think the problem was with the FET,

have you installed the mic shell when testing it cause it will sure hum crazy with no shell,

dan,

The FET has no Wiper , the Potentiometer Does,
the way to do this is to wire the pot for calibration and then install the resistor ,
the new version of the board allow a much better package for the pot or the resistor , <
yes you will need to recalibrate to make sure you have secure connection for R11 (pot or resistor)

Let me know how you make out,
Best,
dAn

Hey Dan,
I got a bad news that I don't understand how it could possible Pin 2 and Pin 3 are shorting and I can't find how I can't find a solution can't understand... the bad news is that my HD Omni's 1st and 2nd channel are dead! :-[ what was the reason I don't know... maybe the shorting issue did it but I'm not sure... Anyway I can't find the problem! everything looks like ok but there is something wrong with my build...
Thanks

PS: wiper=> the second pin of 2N3819

a good way to find out is to remove the transformer secondary wiring and then unsolder pin 2 and 3 from the xlr pad on the pcb and test again ,
look on th reference schematic on page 1 and see why you get a shorts, check the solder on the pcb to make sure there is no bridging also and checks cap for shorts,  if you had a short you would have no signal at all,  sometimes shorting the input of of pre is a way to find where the noise is coming from the electronics or a groundloop , you might have an issue with the phantom power tough but since your phantom voltage looks fine ,  it sure is must be a simple thing,

Hope this helps,
Dan,

 

[jandoste]

Hey Dan,
The cinemag was causing it(shorting)! So I removed the transformer secondary wiring and now it's ok!
My question is that now can I solder two transformer's (secondary) wires to XLR pad?

Thanks

 

[poctop]

Hey Dan,
The cinemag was causing it(shorting)! So I removed the transformer secondary wiring and now it's ok!
My question is that now can I solder two transformer's (secondary) wires to XLR pad?

Thanks

i just want to make sure you are not confusing low resistance for a short , what is the exact resistance in ohm you read from the transfo secondary ,

D

 

[kante1603]

i just want to make sure you are not confusing low resistance for a short , what is the exact resistance in ohm you read from the transfo secondary ,

D

That's what I thought too.
Using a continuity check function is wrong here,you want to look for dcr.
Once on it best check both primay and secondary windings,also for shorts between them.
This way we can sort out if your issues are transformer related or not.

Best,

Udo.

 

[jandoste]

Thanks Dan&Udo,
the transfo reading is 35.5R
Thanks

i just want to make sure you are not confusing low resistance for a short , what is the exact resistance in ohm you read from the transfo secondary ,

D

 

[kante1603]

Looks about right.What about the primary,should read higher,some hundred ohms or so.
And is there any connection between it and the secondary?

Udo.

 

[jandoste]

Thanks Udo,
the primary reads 1k4 and there is any connection between them.  ???
I just didn't understand what I must do with the wiper of trim? Do I need to connect it to grnd during testing?
Thanks

Looks about right.What about the primary,should read higher,some hundred ohms or so.
And is there any connection between it and the secondary?

Udo.